1. INTRODUCTION Marine microbial biotechnology has opened up unexpected new ways for finding new organism for trapping their potential resources. Silver nano particles (AgNPs), are the noble metal nano particles that has being studied extensively due its various biological properties. Silver is a nontoxic, safe inorganic antibacterial agent used for centuries and it has the capability of killing different type of diseases causing microorganisms. Due to the properties of silver at the nano level, nanosilver is currently used in an increasing number of consumer and medical products.

2. The remarkably strong antimicrobial activity is a major reason for the recent increase in the development of products that contain nanosilver. The main challenge in nanomaterials synthesis is the control of their physical properties such as obtaining uniform particle size distribution, identical shape, morphology, chemical composition and crystal structure. Nanoparticles have found uses in many applications in different fields, such as catalysis, photonics, and electronics. Nanoparticles usually ranging in dimension from 1-100 nanometers (nm) have properties unique from their bulk equivalent.

3. With the decrease in the dimensions of the materials to the atomic level, their properties change. The nanoparticles possess unique physico-chemical, optical and biological properties which can be manipulated suitably for desired applications. Hence the present study is aimed to synthesis and characterize silver nanoparticles obtained by use of a marine bacterial strain and its various biological activities.

4. MATERIALS AND METHODS CHEMICALS:- Silver nitrate Merck (Germany) , Zobell media was procured from Hi media ISOLATION OF BACTERIA:-10l of sea water sample was spreaded over the surface of the marine agar. The individual black Colony was taken and maintained as stock culture at 30 C in marine agar test tubes slants. The selected strain was streaked on the Petri plate and continued for the further process.

5. FATTY ACID METHYL ESTERS:- The bacterial strain were cultured onto Trypticase Soya Broth Agar (TSBA) media at 30C for 24 hours. The fatty acids were extracted and methylated to form Fatty Acid Methyl Esters (FAME).These FAMEs were analyzed using Gas Chromatography (Agilent 6850 Series II) with the help of MIDI Sherlock software for FAME. The Aerobic library was used for comparing the results.

6. 16 rRNA GENE SEQUENCING:- The purified bacterial isolates were cultured in saline nutrient broth (7% NaCl) i. It was centrifuge at 4500 rpm for 10 min, at 40C, and twice washing with distilled water, the pellets were selected for DNA extraction an PCR amplification. ii. Bacterial DNA was extracted by heat extraction method. iii. The 16S rRNA gene was amplified by PCR, using the universal prokaryotic primers. iv. PCR was performed in a final volume of 50 l containing PCR amplification buffer, Taq DNA polymerase, dNTPs, template DNA, primer

7. Contd. v. The samples were electrophoresed in a 1% (w/v) agarose gel, a single *800 bp DNA fragment was cut and extracted from the gel, using a Core Bio Gel Extraction Kit. vi. The sequence similarity searches were done using the BLAST program that is available from the National Centre for Biotechnology Information (NCBI).

8. BIOSYNTHESIS OF Ag-NPs:- Bacterial strain was grown in Zobell marine broth. i. The final pH was adjusted to 7.0. The flask were incubated at 200 rpm (28C). ii. After 24hrs of incubation, the biomass was separated by centrifugation. iii. The supernatant and pellet was challenged with equal amount of with various concentrations (0.5, 1.0, 1.5, 2.0, 2.5 mM) of silver nitrate solution (prepared in deionized water) and incubated in dark condition at 280C. iv. Simultaneously, a positive control of silver nitrate solution and deionized water and a negative control containing only silver nitrate solution were maintained under same conditions.

9. UV -VISIBLE SPECTRAL ANALYSIS:-The synthesized silver nanoparticle solution was observed in UVvisible spectra, the change in colour of this solution were recorded in ELICO SL-159 Spectrophotometer in the range of 350470 nm. SCANNING ELECTRON MICROSCOPE:- After freeze drying of the purified silver particles, the size and shape were analyzed by scanning electron microscopy (JOEL-Model 6390).

10. Fourier-transform infrared (FT-IR) chemical analysis:- It measure the biotransformed products present in extracellular filtrate were freeze-dried and diluted with potassium bromide in the ratio of 1:100. The FT-IR spectrum of samples was recorded on a FT-IR instrument (Digital Excalibur 3000 series, Japan) with diffuse reflectance mode (DRS-800) attachment. All measurements were carried out in the range of 4004,000 cm-1 at a resolution of 4 cm-1. X-RAY DIFFRACTION ANALYSIS:- The samples were embedded with the silver nanoparticles was freeze-dried, powdered and used for XRD analysis. The spectra were recorded in Philips_automatic X-ray Diffractometer with Philips PW 1830 X-ray generator. The diffracted intensities were recorded from 30 to 90 2h angles.

11. ANTIBACTERIAL ACTIVITY:- Muller Hilter agar was prepared & medium was sterilized by autoclaving at 121C for 15 minutes at 15 psi pressure and was used to determine the antibacterial activity of Ag-NPs from pigmented black bacteria. Sterile molten cool (45C) agar was poured aseptically into sterile petri plates (15 ml each) and the plates were allowed to solidify at room temperature in sterile condition. The plates were allowed to solidified & after drying the plates were seeded with appropriate microorganisms by streaking evenly on to the surface of the medium with a sterile spreader and wells (8 mm diameter)

12. Contd. were cut out from the agar plates using a sterile stainless steel bore and filled with 0.1ml of the each synthesized silver nanoparticles solution in respective wells Tetracycline and double distilled water were used as positive and negative control respectively. Then the plates were incubated at 37C for 24 hrs in the next day the zones of inhibition were measured with a measuring scale. This experiment was carried out in triplicate for their confirmation. The results were read by the presence or absence of zone of inhibition.

13. ANTI FUNGAL ACTIVITY:- For determination of antifungal activity from black pigmented bacteria cool sterile molten agar was poured aseptically into sterile petri plates (15ml each) & allowed to solidify at room temperature in sterile conditions. After solidification and drying, the plates were seeded with appropriate micro organisms by spreading evenly on to the surface of the medium with a sterile spreader and wells (8 mm diameter) were cut out from the agar plates using a sterile stainless steel bore and filled with 0.1ml of the each synthesized silver nanoparticles solution in respective wells. Nystatin and distilled water were used as positive and negative control respectively. Then the plates were incubated at 37C for 4 days, the zones of inhibition were measured.

14. RESULTS & DISCUSSION Marine water samples collected from Nellore marine area were used to isolate potential microbial strains using Zobell marine agar plates. After incubation at 30oC several colonies developed & all isolated strains was screened to produce silver nanoparticles synthesis . A total of 30 different bacterial strains were isolated, purified and preserved. Among the isolated strains, the strain which produced a brown pigment with good antibacterial activity against both gram positive and gram negative bacteria was selected for further studies and designated as PSK09.

15. Figure 1:-The pure culture of marine isolate PSK09

16. MOLECULAR IDENTIFICATION:- i. The bacterium was identified as Pseudomonas aeruginosa using 16sRNA, the bacterial DNA was isolated & the 16S rRNA sequence was amplified and sequenced. ii. 16S rRNA sequence of the bacterium obtained was compared with the non-redundant BLAST database to obtain the sequences that displayed maximum similarity. iii. All the sequences reported by BLAST revealed that the bacterial species showed a very high percentage of similarity (99%) with the sequences of Pseudomonas aeruginosa with high score & E-value being zero. iv. Sequence with maximum similarity used for alignment using CLUSTAL W2 to derive the phylogenetics relationship. v. mv. There exists a clear evolutionary relation between all the 16S rRNA sequences as this represents a highly conserved sequence.

17. v. There exists a clear evolutionary relation between all the 16S rRNA sequences as this represents a highly conserved sequence. Figure 2: Showing the 16s rRNA band of Pseudomonas aeruginosa

18. SYNTHESIS OF SILVER NANOPARTICLES:- For the conformation of synthesis of nanoparticles in the medium was characterized by the changes in color of the reaction mixture from light yellow to light brown after 24h of incubation. Addition of Ag+ ions to the supernatant and pellet culture, samples showed the results as color formation to brown, the color intensity increased with period of incubation due to the reduction in Ag0 .Control (without silver nitrate) showed no color formation in the culture when incubated for the same period and condition. In the supernatant culture no color changes seen on incubation period and the pellet culture containing Ag+ ions shown the change of color to brown as shown in figure. Synthesis of silver nanoparticles also depends on incubation period of the culture

19. Fig4:-Showing SEM micrographs of silver nanoparticles synthesized from marine bacteriaextracts Fig5:XRD analysis of silver nano particle

20. UV spectrophotometer:- Reduction of silver ions into silver nanoparticles using bacterial culturescwas evidenced by the visual change of colour from yellow to reddish brown due to excitation of surface plasmon vibrations in silver nanoparticles. The synthesized silver nanoparticles was then characterized by UV spectrophotometer. The UV-visible spectra recorded at different time intervals showed increased absorbance with increasing time of incubation. The absorbance spectra of reaction mixture containing aqueous solution of 1mM silver nitrate and the pellet of Pseudomonas aeruginosa after incubation. The band corresponding to the Surface plasmon resonance at 410 to 430 nm. The strong peak at 420 nm.

21. FTIR ANALYSIS: The characterization of the nanoparticles and the resulting resulting silver nanoparticle Was analyzed by FTIR.FTIR absorption spectra of the silver nano particle solution was shown in figure(Fig5). The absorbance bands analysis in bioreduction and absorbed in the regions are 1735.85.61, 1602.70,1533.93, 1396.34, 1363.15. X-ray diffraction analysis: XRD analysis of lyophilized cell pellets is powdered and used for XRD analysis. The spectra were recorded. All patterns indicate the occurrence of five diffraction peaks which are consistent with the (11 1), (2 0 0), (2 2 0), (3 3 1) and (2 2 2) diffraction of face centre cubic silver.(Fig 6)

22. Fig:6:FT-IR spectrum recorded with synthesized silver nanoparticles

23. DISCUSSION Reduction of silver ion into silver particles during exposure to the pellet could be followed bycolor change. Silver nanoparticles exhibit dark yellowish-brown color in aqueous solution due to the surface plasmonresonance phenomenon.The present study emphasizes the use of marine bacteria for the synthesis of silver nanoparticles with potent biological effect In this study, the application of silver nanoparticle as an antimicrobial and anti fungal activity. Microorganism plays a very important function in sustaining soil health, ecosystem functions and production. Extracts from microorganisms may reduced as decreasing and capping agents in AgNPs synthesis.

24. Contd. The decrease of silver ions by combinations of bio-molecules found in these extracts such as enzymes, proteins, amino acids, polysaccharides and vitamins is environmentally benign, yet chemically complex. But, the mechanism which is broadly acknowledged for the synthesis of silver nanoparticles is the occurrence of enzyme Nitrate reductase These facts and figures farther sustained that the marine isolate, Pseudomonas aeruginosa has promise to reduce the silver ions to nanoparticles, and biosynthesis of metalThe size ranges of silver nanoparticles produced by the CS 11 (4294 nm) fall closer to the size of silver nanoparticles produced by other bacteria

25. CONCLUSION In conclusion, silver nanoparticles are having wide applications in various fields like antimicrobials, paints preservatives, and cosmetics. So improving of synthesis for nanoparticles production is the major object in the field of nanotechnology. The characterization of silver ion exposed to microbial strain and the reduction of silver nitrate to silver nanoparticles was confirmed by UV visible spectrophotometer. The toxicity study of The usage of marine bacteria is the good approach to the production of Eco-friendly and costs effectual silver nanoparticles. The nanoparticles proved excellent antimicrobial activity. Hence, the biological approche appears to be cost efficient alternative to conventional physical and chemical methods of silver nanoparticles synthesis and would be suitable for developing a biological process for commercial large scale- production.

26. Figure 4:-Antibacterial activity of silver nano particles against bacteria

27. Strain Name Silver nano particles Culture filtrate Silver nitrate Streptomyci n Bacilllus sphericus 22 mm 8 mm 18 mm 25 mm Micrococcus luteus 35mm 22mm 21mm 33mm Pseudomona s aeruginosa 20mm 18mm 15mm 30mm Bacillus cereus 28mm 10mm 20mm 30mm Proteus vulgaris 22mm 18mm 18mm 32mm Escherichia coli 22mm 18mm 20mm 25mm Bacillus subtilis 25mm 20mm 20mm 34mm Salmonella paratyphi 28mm 18mm 20mm 30mm

28. Table showing the antifungal activity of silver nanoparticle synthesized from bacterial pellet Zone of inhibition (ZOI in mm). Test Organisms Silver nanoparticles Standard Aspergillus fumigatus 06 12 Aspergillus flavus 03 18 Aspergillus niger 00 19 Candida 03 20

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